Psilotum nudum COMMON NAME Whisk fern, skeleton fork fern FAMILY Psilotaceae AUTHORITY Psilotum nudum (L.) P. Beauv. FLORA CATEGORY Vascular – Native ENDEMIC TAXON No ENDEMIC GENUS No ENDEMIC FAMILY Moturua, Coromandel. Photographer: John No Smith-Dodsworth STRUCTURAL CLASS Ferns NVS CODE PSINUD CHROMOSOME NUMBER 2n = 208 CURRENT CONSERVATION STATUS 2012 | Not Threatened At Moturua, Coromandel. Photographer: John Smith-Dodsworth PREVIOUS CONSERVATION STATUSES 2009 | Not Threatened 2004 | Not Threatened DISTRIBUTION Indigenous. New Zealand: Kermadec Islands (Raoul Island), North Island (North Cape south to the southern shore of Lake Taupo and Tokaanu). HABITAT Coastal to monatane. In the northern part of its range Psilotum is usually a local component of coastal forest where it grows on the forest floor, in rock piles and on cliff faces. It is also occasionally epiphytic on trees such as pohutukawa (Metrosideros excelsa). On Raoul Island it is an abundant ground cover in the “dry” forest type on that island. In the North Island outside Northland and the Coromandel Peninsula, Psilotum becomes increasingly tied to geothermally active sites where it usually grows on cliff faces and warm soil around fumaroles. In the ignimbrite country north of Lake Taupo, and also along the western shore of Lake Taupo, Psilotum is at times a very common species growing in the joints of columnar ignimbrite. On the western shoreline of Lake Taupo in this type of habitat plants can grow very large, and they may grow right down into the flood-line where they are often associated with Lindsaea viridis. Around Auckland City Psilotum is a very common, though easily overlooked plant of stone walls (especially basalt or concrete retaining walls). FEATURES Epiphytic or terrestrial plants. Rhizome branching, short- to long-creeping, usually clumped. Aerial shoots 50-100-200(-900) mm, dark green, green or yellow depending on growing conditions, erect, firm of sometimes flaccid in shaded situations, branched repeatedly in different planes in the upper part. Branches prominently ribbed 3-7×, subterete in cross-section, to 4.5 mm diameter; stomata restricted to furrows between ribs. Sterile leaves 1.0-2.5 mm long, pale yellow (translucent toward apices), restricted to ribs, subspiral, terete. Synangia 1.5-2.0 × 2.0-2.5 mm, yellow, globular, partitioned in 3 segments. SIMILAR TAXA A very distinctive species unlike to be confused with any other fern. Psilotum is easily recognised by the almost distinctive broom-like growth habit, with numerous twiggy, coralloid, whip-like branches usually bearing bright yellow, globular synangia (which are always partitioned in 3). Psilotum could be confused with species of broom (Cytisus and Carmichaelia) as these sometimes grow in habitats favoured by Psilotum. They may be distinguished from Psilotum by the presence of trifoliolate leaves, flowers and/or seed capsules, and if sterile by non-rhizomatous growth habit, and the presence of a distinct root system bearing rhizobium nodules. FLOWERING N.A. Spore producing FLOWER COLOURS No flowers FRUITING N.A. Spore producing PROPAGATION TECHNIQUE Easily grown from rooted pieces. Best grown in a well drained substrate, planted in full sun. Once established very hard and drought tolerant. Psilotum makes an excellent pot plant, a use to which it often put overseas. ETYMOLOGY psilotum: From Greek psilos ‘bare’ or ‘naked’ referring to the apparent nakedness of the stems nudum: Bare WHERE TO BUY Not commercially available. ATTRIBUTION Fact sheet prepared for NZPCN by P.J. de Lange (7 May 2011). Description adapted from Chinnock (1998). REFERENCES AND FURTHER READING Chinnock, R.J. 1998: Psilotaceae. Flora of Australia 48: 47–53. CITATION Please cite as: de Lange, P.J. (Year at time of access): Psilotum nudum Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/psilotum-nudum/ (Date website was queried) MORE INFORMATION https://www.nzpcn.org.nz/flora/species/psilotum-nudum/.